As is known, sensors of various types are used in a variety of applications. Sensors including one or more sensing elements (e.g., pressure sensing elements, temperature sensing elements, light sensing elements, acoustic sensing elements, and magnetic field sensing elements) are used to detect one or more parameters (e.g., pressure, temperature, light, sound, magnetic field). Magnetic field sensors, for example, are circuits including one or more magnetic field sensing elements, generally in combination with other circuit components (e.g., analog, digital and/or mixed signal components), and are used to detect a magnetic field.
In motion (e.g., rotation) detectors, for example, a magnetic field sensor may be used to detect motion of an object, such as a ferromagnetic object, for example, a gear or ring magnet. A magnetic field associated with the object is typically detected by one or more magnetic field sensing elements, such as Hall effect elements and/or magnetoresistance elements, which provide a signal (i.e., a magnetic field signal) proportional to an applied magnetic field.
Magnetic field sensing elements are typically sensitive to magnetic field strength and temperature. A magnetic field sensing element's response to an applied magnetic field (e.g., a magnetic field as may be affected by motion of a ferromagnetic object) may, for example, be a function of various factors including design parameters, such as materials, layer thickness and other dimensions, etc. Manufacturing tolerances and/or defects or irregularities (e.g., layer thickness or layer quality defects) formed during manufacture and/or use of magnetic field sensing elements may adversely affect a magnetic field sensing element's expected response (e.g., change in resistance) to an applied magnetic field and, thus, adversely affect the reliability of a resulting device (e.g., motion detector) in which the magnetic field sensing elements are provided.
In high precision sensing applications such as automobiles, accuracy in magnetic field sensing, such as may be used to detect motion of a target object, can be critical. Engine ignition timing, for example, depends on consistent detection accuracy. When magnetic field sensing elements of a magnetic field sensor integrated circuit (IC) in an engine ignition timing system respond to a magnetic field in an unknown and/or undesirable manner, detection accuracy by the magnetic field sensor IC, and the resulting accuracy or performance of the engine ignition timing system, can be negatively impacted (e.g., due to sudden unexpected changes in an output of magnetic field sensing elements).